The present invention is generally related to telecommunication systems, and, more particularly, to techniques for determining loading of a communications system, such as may shared by a plurality of user terminals.
Telecommunication network systems, including by way of example, cellular communication systems, such as Advanced Mobile Phone Service (AMPS) and Global System for Mobile Communications (GSM); and trunking systems, such as Enhanced Digital Access Communication Systems (EDACS), are conceptually made up of a number of communication or radio xe2x80x9cchannelsxe2x80x9d which may be either a physical pair of radio frequencies, or a logical collection of data bursts. These channels are arranged as inbound and outbound communications paths to and from a repeater, or base station. One channel is usually designated as a control channel, with digital control messages being transmitted continuously from the repeater, the remaining channels being designated as working or traffic channels.
Under presently known techniques, a terminal on the communication system would decode the control channel, and then evaluate the messages that are specifically directed or addressed to that terminal, and discard all other messages. That is, messages not addressed to that terminal are discarded.
When accessing the system in order to transfer a periodic message or update, the terminal will attempt an access. In general, there are three basic responses the terminal can receive: 1) A channel assignment, in which case the terminal will proceed with the transaction; 2) An indication that the system is busy (a channel or some other necessary resource is unavailable at that time), in which case the terminal will reattempt the access later; or 3) no response, in which case the terminal will assume that there was a collision between the data transmitted by that terminal to the base station and some other transmission. Typical system-states corresponding to the foregoing responses respectively are: 1) The system is relatively unloaded; 2) The working channel load is limiting communication; and 3) The inbound control channel load is limiting communication. The latter two states are the ones of primary interest in the loading design of a communications system.
A typical communications system has peak loading periods that the system has to be designed for, and during the majority of the other times the system capacity may be substantially underutilized. For a system that has the vast majority of their calls at essentially the same relative priority, that would be the end of the story in terms of practical utilization of any systematic loading optimization. The system would have to be designed for the worst case, and the peak loading contention would be resolved by queuing calls and automated retrying if a signaling collision occurs.
New and existing technologies are finding ever-increasing applications in communications systems which, when implemented, can provide useful but not necessarily critical information to the system users. The drawback of some of these applications is a tremendous increase in system loading that is relatively independent of the time of day. Under present system loading contention practices, this increased loading can detrimentally impact both non-critical (lower priority) and critical (high priority) communications and result in unacceptable access time for communication of critical messages.
Presently available techniques for determining the level of activity on a cellular communications system generally require the inclusion of dedicated software and messaging into each base station of the system, and further require the inclusion of appropriate information transport into the over-the-air channel protocols. Unfortunately, under these prior art techniques, the implementation of the system loading software within the infrastructure components (base stations, switches, control systems, etc.) is highly complex, time consuming, and, consequently, these implementations generally require the allocation and consumption of costly and scarce resources. As suggested above, this software must be in place on all of the base stations within a network in order to realize any benefit from the system loading determination. Finally, it is unfeasible and/or impractical to implement such prior art techniques on an already deployed communications system, without changing the installed software, which in some instances may well no longer be supported or maintained.
Thus, it would be desirable to provide techniques for determining the level of activity on a cellular communications system that are not subject to the above-described disadvantages. For example, it would be desirable to determine the level of activity on a given communications system by observing the overall control channel utilization. More particularly, it would be desirable to make such a system-loading determination by utilizing information, which, although already available to respective terminals in the system, under prior art techniques, would have been discarded or ignored. That is, it would be desirable to use system information for determining system loading regardless of whether or not that information is specifically addressed to a respective terminal, e.g., any terminal attempting to access the system. This previously discarded information could be used to give a measure of the system loading by observing the activity level on the controlling channel. This system loading information has significant value in the initiation of non-critical transactions that occur over a given communications system, such as vehicle position updates, periodic equipment status messages, etc. This allows a degree of prioritization to be performed by the terminal equipment without the necessity for changes in the infrastructure hardware or software, and/or complex information gathering, which could further burden the load of the system.
Generally, the present invention fulfills the foregoing needs by providing in one aspect thereof, a method for determining loading of a communications system shared by a plurality of user-terminals. The method allows a respective terminal to monitor a control channel including logical messages therein. The monitoring of the messages in the control channel is performed regardless of whether or not the logical messages are specifically addressed to that terminal. The method further allows for estimating a parameter indicative of system loading based on information extracted from the monitored logical messages.
The present invention further fulfills the foregoing needs by providing in another aspect thereof, a processor for determining loading of a communications system shared by a plurality of user-terminals. The processor includes a radio channel monitor configured to monitor in a respective terminal a control channel including logical messages therein. The monitor is further configured to monitor logical messages in the control channel regardless of whether or not the logical messages are specifically addressed to that terminal. An estimator is configured to estimate a parameter indicative of system loading based on information supplied by the radio channel monitor.